Product piracy is a worldwide problem. It is estimated that over 5% of all world trade is in counterfeit goods, adding up to about $250 billion per year. Such product piracy affects both physical products, such as watches, spare parts and medicine, as well as non-physical products, such as music and computer software. However, in some cases, the non-physical products are wrapped in a physical package or stored on some sort of physical media, for example, music on a cd, whereby also non-physical products in some cases may be seen as physical products.
In order to overcome this piracy problem, a number of different technical solutions for checking the authenticity of a product have been developed. One such solution is, for example, a bar code system connected to a database, in which individual information in relation to relevant items is held. However, bar codes can easily be copied. Furthermore, holding information individually for a large number of items in a variety of countries requires a lot of administration in order to be updated. Therefore, other types of technical solutions, not requiring a central administration, have been developed.
A Physical Unclonable Function (PUF) is a function that is realized by a physical system, such that the function is easy to evaluate but the physical system is hard to characterize. Furthermore, the physical system is hard to clone physically. PUFs are for example described in R. Pappu, Physical One-Way Functions, Ph.D. thesis, MIT, 2001.
International Patent Application No. WO2007/031908 describes a physical uncloneable function (PUF) device for determining authenticity of an item, wherein a PUF pattern of the PUF device is damaged when using the item for the first time. The PUF pattern, giving rise to a cryptographic key, is damaged when using or opening the item. When the PUF pattern is damaged, the original cryptographic key is destroyed and can no longer be restored. Moreover, the damaged PUF pattern results in an unpredictable (random) new key that is inconsistent with the reference value used for authentication. Consequently, it is virtually impossible to fake authenticity for an item after the first usage.
Often, goods are shipped that are vulnerable to some environmental influence, for example, high/low temperature, high acceleration, exposure to light, chemicals, moisture, etc., or goods that simply degrade with time.
Special labels exist in the market that indicate if excessive conditions have occurred, for example, by irreversibly changing color. However, dishonest parties could replace an ‘invalidated’ label by a fresh one that does not indicate that a problem has occurred. Thus, the (re-)sale conditions for that item will appear to be met. The replacement could be a fake label or simply another authentic one available to a party legally within the supply chain. This problem can arise because the authentic labels cannot be mutually distinguished and are typically provided in bulk, for example on a roll.